Kalundborg industrial symbiosis

Industrial symbiosis reduces waste and pollution

Kalundborg, Denmark, is a leading example of industrial symbiosis (IS). IS is where coordination among different kinds of industrial operations enables the use of each other’s by-products and wastes, closing loops of energy, water, materials and waste. Centred on a combined-heat-and-power (CHP) station, Kalundborg’s IS-network involves many kinds of actors. It has achieved high savings in resources and pollution reductions.

The Danish municipality of Kalundborg is widely considered the world’s first and most advanced example of industrial symbiosis (IS). IS is a term for coordination among industries of different types located near one another, creating a kind of ecosystem with closed-loop flows of energy, water, materials, wastes, etc. When these are used as resources, there are ecological footprint and monetary savings in resource-supply and waste-disposal, for both individual companies and society. A region that enables IS can increase economic activity without equivalent growth in waste disposal into its environment, or increased demand for resources like energy and water (see also Stockholm).

Symbiosis by exchange
In Kalundborg, IS involves many exchanges. Process steam from the Asnaes combined heat and power (CHP) station is used by an oil refinery (Statoil), a biotechnology company (Novo Nordisk), and a biotechnology company (Novozymes). This reduced oil consumption by 20,000 tonnes and water consumption by 25% in one annual estimate.

Ash from Asnaes is used by construction and cement companies. Gypsum from Asnaes' sulphur scrubbers is made into plasterboard. The CHP station's cooling water is used in aquaculture and its lime is used as farming fertilizer. By-products of Novo Nordisk’s production enzymes have also been transformed into fertilizer at a large scale (1.5 million m3 annually).

Savings in resources
Measures of water-related IS show that more than 95% of the CHP plant’s input water and 98% of the refinery’s input water have been used in the IS network. More than 50% of input energy at one facility is from steam energy in the network. Another company has reduced its oil consumption costs up to 95% by using energy (gas) from the network.

However, fossil fuels are still used intensively: the Asnaes CHP station's energy sources are coal and heavy fuel oil. So while the concept of IS is completely in synch with the transition to a renewable future, the challenge remains to get out of fossil fuel dependency in Kalundborg.

Scarce groundwater drives cooperation
In Kalundborg, the development of IS was driven partly by low groundwater supplies, which meant that expanding production in the area required a diversified water supply. Development of the IS network has centred on the CHP plant, in particular because of its water-consuming processes that have enabled cooling water and wastewater exchanges.

A degree of coordination by government and among network actors is the basis for industrial symbiosis. For example, key factors are satisfying the regulatory and information requirements for resource recognition and exchange, and creating sufficiently large economies of scale.